Integrated circuits are implemented e.g. as system-on-chip on an ASIC; ASIC=Application Specific Integrated Circuit. An ASIC comprises special circuits, which are tailored to customers' wishes. These perform specific tasks. In telecommunications, for example, they are used for processing VoIP signals, DSL, ATM, SDH, SONET, UMTS, GSM, LMDS or ISDN signals; VoIP=Voice over Internet Protocol, DSL=Digital Subscriber Line, ATM=Asynchronous Transfer Mode, SDH=Synchronous Digital Hierarchy, SONET=Synchronous Optical Network, UMTS=Universal Mobile Telecommunication System, GSM=General System Mobile, LMDS=Local Multipoint Digital System, ISDN=Integrated Services Digital Network. They thus serve for processing speech, data, video, Internet web pages, etc.
An integrated circuit has e.g. a special processor platform for implementing general but also application-specific tasks. This processor platform can be used for any applications; the same processor platform for example in DSL chips, ATM chips etc. It includes a processor and supplies computing capacity.
The processor platform has several components, some components being connected to a fast AMBA-AHB bus, e.g. a processor, a ROM controller, a RAM controller, and other components being connected to a slow AMBA-APB bus, e.g. an interrupt controller, a real time counter; ROM=Read Only Memory, RAM=Random Access Memory. The question of which component is connected to which bus depends on the access speed, the processing speed and the frequency of use of the component.
For some components, such as the ROM controller and the RAM controller, which are hereinafter referred to as modules, address ranges comprising several addresses should be assigned. For each module, a predetermined address range within an address space is reserved before start-up. In addition, one address range is dual-assigned, for the ROM controller on the one hand and the RAM controller on the other hand. Memory management allocates the additionally specified address range to the ROM controller in the first place. If the address range is no longer needed for the ROM controller, e.g. after the boot operation, a one-time switch occurs to transfer the specified address range to the RAM controller.